Cross-frame progressive spoiling support for reduced network bandwidth usage

ABSTRACT

An invention is disclosed for efficiently processing and transmitting graphics data in a remote desktop environment. In embodiments of the invention, a connection is established between a remote desktop server computer and a remote desktop client computer. The remote desktop server computer may process graphics data representative of a remote user desktop. The remote desktop server computer may divide the remote desktop screen in data regions and portions. The remote desktop server computer may then encode and transmit each region to the remote desktop client computer at a certain quality that may be adjusted progressively across the screen frames. The remote desktop server computer may also stop encoding and transmitting the portions of the data region that would not be visible to a user when the region is rendered on a display. The remote desktop user experiences an image quality gradually improving with each frame containing information about the image.

BACKGROUND

Remote computing systems can enable users to remotely access hostedresources. Servers on the remote computing systems can execute programsand transmit signals indicative of a user interface to clients that canconnect by sending signals over a network conforming to a communicationprotocol such as the TCP/IP protocol. Each connecting client may beprovided a remote presentation session, i.e. an execution environmentthat includes a set of resources. The clients may use remotepresentation protocols such as the Remote Desktop Protocol (RDP) toconnect to a server resource.

In a remote presentation session, a client sends a serverlocally-received input, such as mouse cursor movements and keyboardpresses. In turn, the server receives this input and performs processingassociated with it, such as executing an application in a user session.When the server performs processing that results in an output, such as agraphical output, the server sends this output to the client forpresentation. In this manner, applications appear to a user of theclient to execute locally on the client when, they in fact, execute onthe server.

Further, in the remote presentation session, data representing graphicsto be transmitted to the client are typically compressed by the server,transmitted from the server to the client through a network, anddecompressed by the client and displayed on the local user display.While there are known techniques for the server to compress and transmitthe graphics data to the client through a network, there are also manyunresolved problems. For example, problems arise when the networkbandwidth constraints the size of the graphics data that can betransmitted to the client, resulting in network latencies and in anegative remote user experience.

Various schemes may be used to minimize the size of the graphics data ina remote presentation session that need to be encoded and transmitted toa remote computing device. Such schemes may include dividing thegraphics data into portions, and encoding and transmitting only theportions that have changed since a previous transmission. However, suchschemes do not account for and are applied independently of theavailable network bandwidth and the amount of data to be processed.Thus, such schemes do not optimally resolve the problems of networklatencies and their negative impact to the remote user experience.

SUMMARY

In various embodiments, methods and systems are disclosed for optimizingthe processing and transmitting of graphics data by performing variousprogressive encoding and spoiling schemes. When the network bandwidth islimited and/or the amount of data to be processed is large, progressiveencoding and spoiling reduces the network bandwidth usage and the framelatency. For example, when using a progressive encoding and spoilingscheme, a graphics data frame is divided into data regions and each dataregion is encoded and transmitted to the client at a certain quality.The data regions can be further divided between regions containingnatural images and regions containing text images. The quality of eachdata region in a graphics data frame can be progressively improved asthe graphics data frame is updated. The quality can also be dynamicallyadjusted depending on the available network bandwidth and the amount ofdata to be processed. In addition, to ensure the coherence of thegraphics data, a future graphics data frame is processed only after acertain quality of the current graphics data frame is reached. However,when a graphics data frame is updated and a portion of a data regionwithin the graphics data frame would no longer be visible to a remoteuser when rendered on the user display, that portion is preferablyspoiled and is not encoded or transmitted. Furthermore, when the qualityof a data region reaches 100%, the data region can be marked as havingfull fidelity and can be cached by the client computer. Finally, toensure readability of text images contained in graphics data regions,the progressive encoding and spoiling scheme can be applied to only dataregions containing natural images rather than text images. As a resultof the progressive encoding and spoiling scheme, the user experiences anatural image quality gradually improving with each frame containinginformation about the image, while being able to read and understand thetext image.

The various progressive encoding and spoiling schemes provide variousbenefits, depending on the system, including: a reduction in networkbandwidth usage with minimal impact to the user experience; a support ofmultiple progressive and non-progressive codecs in seamlessly encodingdifferent screen portions; a support of progressive encoding on screenregions with natural images in multiple quality levels; a support ofdata spoiling by not encoding to a higher quality an unneeded dataportion; and a dynamic adjustment of progressive encoding and spoilingbased on the available network bandwidth and on the amount of data to beencoded.

In addition to the foregoing, other aspects are described in the claims,drawings, and text forming a part of the present disclosure. It can beappreciated by one of skill in the art that one or more various aspectsof the disclosure may include but are not limited to circuitry and/orprogramming for effecting the herein-referenced aspects of the presentdisclosure; the circuitry and/or programming can be virtually anycombination of hardware, software, and/or firmware configured to effectthe herein-referenced aspects depending upon the design choices of thesystem designer.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an example computer system wherein aspects of the presentdisclosure can be implemented.

FIG. 2 depicts an example architecture of the input systems of a remotepresentation session client and server in which embodiments of theinvention may be implemented.

FIG. 3 depicts an operational environment for practicing aspects of thepresent disclosure.

FIG. 4 depicts an example remote presentation session server in whichembodiments of the invention may be implemented.

FIG. 5 illustrates an overview of some of the processes disclosedherein.

FIGS. 6 and 7 illustrate a remote user screen divided into data regionsand portions for compression.

FIG. 8 illustrates an example of an operational procedure for processinggraphics data for transmission to a client computer.

FIG. 9 illustrates an example system and computer-readable medium forprocessing graphics data for transmission to a client computer.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Certain specific details are set forth in the following description andfigures to provide a thorough understanding of various embodiments ofthe disclosure. Certain well-known details often associated withcomputing and software technology are not set forth in the followingdisclosure to avoid unnecessarily obscuring the various embodiments ofthe disclosure. Further, those of ordinary skill in the relevant artwill understand that they can practice other embodiments of thedisclosure without one or more of the details described below. Finally,while various methods are described with reference to steps andsequences in the following disclosure, the description as such is forproviding a clear implementation of embodiments of the disclosure, andthe steps and sequences of steps should not be taken as required topractice this disclosure.

It should be understood that the various techniques described herein maybe implemented in connection with hardware or software or, whereappropriate, with a combination of both. Thus, the methods and apparatusof the disclosure, or certain aspects or portions thereof, may take theform of program code (i.e., instructions) embodied in tangible media,such as floppy diskettes, CD-ROMs, hard drives, or any othermachine-readable storage medium wherein, when the program code is loadedinto and executed by a machine, such as a computer, the machine becomesan apparatus for practicing the disclosure. In the case of program codeexecution on programmable computers, the computing device generallyincludes a processor, a storage medium readable by the processor(including volatile and non-volatile memory and/or storage elements), atleast one input device, and at least one output device. One or moreprograms that may implement or utilize the processes described inconnection with the disclosure, e.g., through the use of an applicationprogramming interface (API), reusable controls, or the like. Suchprograms are preferably implemented in a high level procedural or objectoriented programming language to communicate with a computer system.However, the program(s) can be implemented in assembly or machinelanguage, if desired. In any case, the language may be a compiled orinterpreted language, and combined with hardware implementations.

The term circuitry used throughout the disclosure can include hardwarecomponents such as hardware interrupt controllers, hard drives, networkadaptors, graphics processors, hardware based video/audio codecs, andthe firmware/software used to operate such hardware. The term circuitrycan also include microprocessors configured to perform function(s) byfirmware or by switches set in a certain way or one or more logicalprocessors, e.g., one or more cores of a multi-core general processingunit. The logical processor(s) in this example can be configured bysoftware instructions embodying logic operable to perform function(s)that are loaded from memory, e.g., RAM, ROM, firmware, and/or virtualmemory. In example embodiments where circuitry includes a combination ofhardware and software an implementer may write source code embodyinglogic that is subsequently compiled into machine readable code that canbe executed by a logical processor. Since one skilled in the art canappreciate that the state of the art has evolved to a point where thereis little difference between hardware, software, or a combination ofhardware/software, the selection of hardware versus software toeffectuate functions is merely a design choice. Thus, since one of skillin the art can appreciate that a software process can be transformedinto an equivalent hardware structure, and a hardware structure canitself be transformed into an equivalent software process, the selectionof a hardware implementation versus a software implementation is left toan implementer.

Embodiments of the invention may execute on one or more computers. FIG.1 and the following discussion are intended to provide a brief generaldescription of a suitable computing environment in which the disclosuremay be implemented. One skilled in the art can appreciate that computersystems can have some or all of the components described herein below.

FIG. 1 depicts an example general purpose computing system. The generalpurpose computing system may include a conventional computer 20 or thelike, including processing unit 21. Processing unit 21 may comprise oneor more processors, each of which may have one or more processing cores.A multi-core processor, as processors that have more than one processingcore are frequently called, comprises multiple processors containedwithin a single chip package.

Computer 20 may also comprise graphics processing unit (GPU) 90. GPU 90is a specialized microprocessor optimized to manipulate computergraphics. Processing unit 21 may offload work to GPU 90. GPU 90 may haveits own graphics memory, and/or may have access to a portion of systemmemory 22. As with processing unit 21, GPU 90 may comprise one or moreprocessing units, each having one or more cores.

Computer 20 may also comprise a system memory 22 in which at leastportions of programming to carry out aspects of the invention may bestored, and a system bus 23 that communicative couples various systemcomponents including the system memory 22 to the processing unit 21 whenthe system is in an operational state. The system memory 22 can includeread only memory (ROM) 24 and random access memory (RAM) 25. A basicinput/output system 26 (BIOS), containing the basic routines that helpto transfer information between elements within the computer 20, such asduring start up, is stored in ROM 24. The system bus 23 may be any ofseveral types of bus structures including a memory bus or memorycontroller, a peripheral bus, or a local bus, which implements any of avariety of bus architectures. Coupled to system bus 23 may be a directmemory access (DMA) controller 80 that is configured to read from and/orwrite to memory independently of processing unit 21. Additionally,devices connected to system bus 23, such as storage drive interface 32or magnetic disk drive interface 33 may be configured to also read fromand/or write to memory independently of processing unit 21, without theuse of DMA controller 80.

The computer 20 may further include a storage drive 27 for reading fromand writing to a hard disk (not shown) or a solid-state disk (SSD) (notshown), a magnetic disk drive 28 for reading from or writing to aremovable magnetic disk 29, and an optical disk drive 30 for readingfrom or writing to a removable optical disk 31 such as a CD ROM or otheroptical media. The storage drive 27, magnetic disk drive 28, and opticaldisk drive 30 are shown as connected to the system bus 23 by a hard diskdrive interface 32, a magnetic disk drive interface 33, and an opticaldrive interface 34, respectively. The drives and their associatedcomputer-readable storage media provide non-volatile storage of computerreadable instructions, data structures, program modules and other datafor the computer 20.

Although the example environment described herein employs a hard disk, aremovable magnetic disk 29 and a removable optical disk 31, it should beappreciated by those skilled in the art that other types of computerreadable media which can store data that is accessible by a computer,such as flash memory cards, digital video discs or digital versatilediscs (DVDs), random access memories (RAMs), read only memories (ROMs)and the like may also be used in the example operating environment.Generally, such computer readable storage media can be used in someembodiments to store processor executable instructions embodying aspectsof the present disclosure and operable to convert computer 20 into aspecial purpose computing device. Computer 20 may also comprise a hostadapter 55 that connects to a storage device 62 via a small computersystem interface (SCSI) bus 56.

A number of program modules comprising computer-readable instructionsmay be stored on computer-readable media such as the hard disk, magneticdisk 29, optical disk 31, ROM 24 or RAM 25, including an operatingsystem 35, one or more application programs 36, other program modules37, and program data 38. Upon execution by the processing unit, thecomputer-readable instructions cause actions described in more detailbelow to be carried out or cause the various program modules to beinstantiated. A user may enter commands and information into thecomputer 20 through input devices such as a keyboard 40 and pointingdevice 42. Other input devices (not shown) may include a microphone,joystick, game pad, satellite disk, scanner or the like. These and otherinput devices are often connected to the processing unit 21 through aserial port interface 46 that is coupled to the system bus, but may beconnected by other interfaces, such as a parallel port, game port oruniversal serial bus (USB). A display 47 or other type of display devicecan also be connected to the system bus 23 via an interface, such as avideo adapter 48. In embodiments, display 47 may comprise atouch-sensitive surface, to which multi-touch input may be made. Inaddition to the display 47, computers typically include other peripheraloutput devices (not shown), such as speakers and printers.

The computer 20 may operate in a networked environment using logicalconnections to one or more remote computers, such as a remote computer49. The remote computer 49 may be another computer, a server, a router,a network PC, a peer device or other common network node, and typicallycan include many or all of the elements described above relative to thecomputer 20, although only a memory storage device 50 has beenillustrated in FIG. 1. The logical connections depicted in FIG. 1 caninclude a local area network (LAN) 51 and a wide area network (WAN) 52.Such networking environments are commonplace in offices, enterprise widecomputer networks, intranets and the Internet.

When used in a LAN networking environment, the computer 20 can beconnected to the LAN 51 through a network interface or adapter 53. Whenused in a WAN networking environment, the computer 20 can typicallyinclude a modem 54 or other means for establishing communications overthe wide area network 52, such as the INTERNET. The modem 54, which maybe internal or external, can be connected to the system bus 23 via theserial port interface 46. In a networked environment, program modulesdepicted relative to the computer 20, or portions thereof, may be storedin the remote memory storage device. It will be appreciated that thenetwork connections shown are exemplary and other means of establishinga communications link between the computers may be used.

In an embodiment where computer 20 is configured to operate in anetworked environment, OS 35 is stored remotely on a network, andcomputer 20 may netboot this remotely-stored OS rather than booting froma locally-stored OS. In an embodiment, computer 20 comprises a thinclient where OS 35 is less than a full OS, but rather a kernel that isconfigured to handle networking and display output, such as on monitor47.

Embodiments of a remote desktop system may execute one or more computersor may have some or all of the components described with respect tocomputer 20 of FIG. 1. A remote desktop system is a computer system thatmaintains applications that can be remotely executed by and displayed onclient computer systems in a remote presentation session. FIG. 2 depictsan example architecture of a remote desktop system. The remote desktopsystem can comprise a remote client computer 200 and a remote servercomputer 220. The remote client computer 200 and the remote servercomputer 220 are configured to conduct a remote presentation sessionwith each other.

As depicted, the remote server computer 220 serves a remote presentationsession to the remote client computer 200 where the remote servercomputer 220 sends client graphical output from executing user a remoteclient session 222. A remote user input is entered at the remote clientcomputer 200. An input manager 202 can process and transfer the remoteuser input over a network (e.g., using protocols based on theInternational Telecommunications Union (ITU) T.120 family of protocolssuch as Remote Desktop Protocol (RDP)) to a remote user application 224on the remote server computer 220. The remote user application 224 canbe executed in a remote client session 222 hosted on the remote servercomputer 220. The remote user application 224 processes the input as ifthe input were entered at the remote server computer 220. The remoteuser application 224 generates remote server output in response to thereceived input and the output is transferred over the network to theremote client computer 200. The remote client computer 200 presents theoutput data to a remote user. Thus, input is received and output ispresented at the remote client computer 200, while processing actuallyoccurs at the remote server computer 220.

In addition to the remote user application 224, the remote clientsession 222 can include a shell and a user interface such as a desktop,the subsystems that track mouse movement within the desktop, thesubsystems that translate a mouse click on an icon into commands thateffectuate an instance of a program, other applications, etc. It shouldbe understood that the foregoing discussion is exemplary and that thepresently disclosed subject matter may be implemented in variousclient/server environments and not limited to a particular remotepresentation product.

In most, if not all remote desktop environments, the remote user inputdata (entered at the remote client computer 200) typically includesmouse and keyboard data representing commands to an application. Outputdata (generated by the remote user application at the remote servercomputer 220) typically includes graphics data for display at the remoteclient computer 200. Many remote desktop environments also includefunctionality that extends to transfer other types of data. In anexample embodiment, graphics data output from the user application 224can be sent to a graphics manager 226 hosted on the remote servercomputer 220. The graphics manager 226 can compress and transfer thegraphics data over the network to a remote user display 204 on theremote client computer 200. The remote user display 204 can render thegraphics output data to a remote user.

Communications channels can be used to extend the RDP protocol byallowing plug-ins to transfer data over an RDP connection. Many suchextensions exist. Features such as printer redirection, clipboardredirection, port redirection, etc., use communications channeltechnology. Thus, in addition to input and output data, there may bemany communications channels that need to transfer data. Accordingly,there may be occasional requests to transfer output data and one or morechannel requests to transfer other data contending for available networkbandwidth. Thus, the available network bandwidth may constrain the datathat can be transferred between the remote server computer 220 and theremote client computer 200 and may result in network latencies impactingthe remote user experience.

Remote services can be provided to at least one client such as theremote client computer 200. The remote client computer 200 can include acomputer terminal that is effectuated by hardware configured to directuser input to a remote client session, such as session 222, and displayuser interface information generated by the session. In anotherembodiment, the remote client computer 200 can be effectuated by acomputer that includes similar elements as those of computer 20 inFIG. 1. Each connecting client can have a remote client session whichallows the client to access data and applications stored on the remoteserver computer 220. In various embodiments, the remote server computer220 may be physical hardware. In other embodiments, some or all of thecomponents of the remote server computer 220 may be instantiated as avirtual machine (VM) such as the VM depicted in FIG. 3. In a VMenvironment, a remote client computer 200 can remotely access the VM andrun a remote presentation session.

Referring now to FIG. 3, depicted are high level block diagrams ofcomputer systems configured to effectuate virtual machines. As shown inthe figures, computer system 300 can include elements described in FIG.1 and components operable to effectuate virtual machines. One suchcomponent is a hypervisor 302 that may also be referred to in the art asa virtual machine monitor. The hypervisor 302 in the depicted embodimentcan be configured to control and arbitrate access to the hardware ofcomputer system 300. Broadly stated, the hypervisor 302 can generateexecution environments called partitions such as child partition 1through child partition N (where N is an integer greater than or equalto 1). In embodiments a child partition can be considered the basic unitof isolation supported by the hypervisor 302, that is, each childpartition can be mapped to a set of hardware resources, e.g., memory,devices, logical processor cycles, etc., that is under control of thehypervisor 302 and/or the parent partition and hypervisor 302 canisolate one partition from accessing another partition's resources. Inembodiments the hypervisor 302 can be a stand-alone software product, apart of an operating system, embedded within firmware of themotherboard, specialized integrated circuits, or a combination thereof.

In the above example, computer system 300 includes a parent partition304 that can also be thought of as domain 0 in the open sourcecommunity. Parent partition 304 can be configured to provide resourcesto guest operating systems executing in child partitions 1-N by usingvirtualization service providers 328 (VSPs) that are also known asback-end drivers in the open source community. In this examplearchitecture the parent partition 304 can gate access to the underlyinghardware. The VSPs 328 can be used to multiplex the interfaces to thehardware resources by way of virtualization service clients (VSCs) thatare also known as front-end drivers in the open source community. Eachchild partition can include one or more virtual processors such asvirtual processors 330 through 332 that guest operating systems 320through 322 can manage and schedule threads to execute thereon.Generally, the virtual processors 330 through 332 are executableinstructions and associated state information that provide arepresentation of a physical processor with a specific architecture. Forexample, one virtual machine may have a virtual processor havingcharacteristics of an Intel x86 processor, whereas another virtualprocessor may have the characteristics of a PowerPC processor. Thevirtual processors in this example can be mapped to logical processorsof the computer system such that the instructions that effectuate thevirtual processors will be backed by logical processors. Thus, in theseexample embodiments, multiple virtual processors can be simultaneouslyexecuting while, for example, another logical processor is executinghypervisor instructions. Generally speaking, and as illustrated by thefigures, the combination of virtual processors, various VSCs, and memoryin a partition can be considered a virtual machine such as virtualmachine 340 or 342.

Generally, guest operating systems 320 through 322 can include anyoperating system such as, for example, operating systems fromMicrosoft®, Apple®, the open source community, etc. The guest operatingsystems can include user/kernel modes of operation and can have kernelsthat can include schedulers, memory managers, etc. A kernel mode caninclude an execution mode in a logical processor that grants access toat least privileged processor instructions. Each guest operating system320 through 322 can have associated file systems that can haveapplications stored thereon such as terminal servers, e-commerceservers, email servers, etc., and the guest operating systemsthemselves. The guest operating systems 320-322 can schedule threads toexecute on the virtual processors 330-332 and instances of suchapplications can be effectuated.

In various embodiments, a remote server computer, such as the remoteserver computer 220 depicted in FIG. 2, can execute multiple remoteclient sessions. Each remote client session, such as the remote clientsession 222, can represent an application environment for a connectingclient. In this example embodiment, a remote server computer cangenerate at least one remote client session for each of the connectingclients as illustrated in FIG. 4. Moreover, as noted above, the remoteserver computer 220 may be a virtual machine that, in turn, executesmultiple remote client sessions.

Depicted in FIG. 4 is computer system 400, which may include circuitryconfigured to effectuate a remote server computer, or in otherembodiments the computer system 400 can include circuitry configured tosupport remote desktop connections. In the depicted example, thecomputer system 400 can be configured to generate one or more remoteclient sessions for connecting clients such as sessions 1 through N(where N is an integer greater than 2). Briefly, a session in exampleembodiments of the present invention can generally include anoperational environment that is effectuated by a plurality ofsubsystems, e.g., software code, that are configured to interact with akernel 414 of computer system 400. For example, a session can include aprocess that instantiates a user interface such as a desktop window, thesubsystems that track mouse movement within the window, the subsystemsthat translate a mouse click on an icon into commands that effectuate aninstance of a program, etc. A session can be generated by the computersystem 400 on a user by user basis by the computer system 400 when, forexample, the computer system 400 receives a connection request over anetwork connection from a client, such as the remote client computer200. Generally, a connection request can first be handled by thetransport logic 410 that can, for example, be effectuated by circuitryof the computer system 400. The transport logic 410 can in someembodiments include a network adaptor; firmware, and software that canbe configured to receive connection messages and forward them to theengine 412. As illustrated by FIG. 4, the transport logic 410 can insome embodiments include protocol stack instances for each session.Generally, each protocol stack instance can be configured to route userinterface output to a client and route user input received from theclient to the session core 444 associated with its session.

Continuing with the general description of FIG. 4, the engine 412 insome example embodiments of the present invention can be configured toprocess requests for sessions; determine the functionality for eachsession; generate sessions by allocating a set of physical resources forthe session; and instantiating a protocol stack instance for thesession. In some embodiments the engine 412 can be effectuated byspecialized circuitry components that can implement some of the abovementioned operational procedures. For example, the circuitry in someexample embodiments can include memory and a processor that isconfigured to execute code that effectuates the engine 412. As depictedby FIG. 4, in some instances the engine 412 can receive connectionrequests and determine that, for example, a license is available and asession can be generated for the request. In the situation where thecomputer system 400 is a remote computer that includes remote desktopcapabilities, the engine 412 can be configured to generate a session inresponse to a connection request without checking for a license. Asillustrated by FIG. 4, a session manager 416 can be configured toreceive a message from an engine 412 and in response to the message thesession manager 416 can add a session identifier to a table; assignmemory to the session identifier; and generate system environmentvariables and instances of subsystem processes in memory assigned to thesession identifier.

As illustrated by FIG. 4, the session manager 416 can instantiateenvironment subsystems such as a runtime subsystem 440 that can includea kernel mode part such as the session core 444. For example, theenvironment subsystems in an embodiment are configured to expose somesubset of services to application programs and provide an access pointto the kernel of the computer operating system 402. In exampleembodiments the runtime subsystem 440 can control the execution ofprocesses and threads and the session core 444 can send requests to theexecutive of the kernel 414 to allocate memory for the threads andschedule time for them to be executed. In an embodiment the session core444 can include a graphics display interface 446 (GDI), a securitysubsystem 450, and an input subsystem 452. The input subsystem 452 canin these embodiments be configured to receive user input from a client401 via the protocol stack instance associated with the session andtransmit the input to the session core 444 for the appropriate session.The user input can in some embodiments include signals indicative ofabsolute and/or relative mouse movement commands, mouse coordinates,mouse clicks, keyboard signals, joystick movement signals, etc. Userinput, for example, a mouse double-click on an icon, can be received bythe session core 444 and the input subsystem 452 can be configured todetermine that an icon is located at the coordinates associated with thedouble-click. The input subsystem 452 can then be configured to send anotification to the runtime subsystem 440 that can execute a process forthe application associated with the icon.

In addition to receiving input from a client 401, draw commands can bereceived from applications and/or a desktop and be processed by the GDI446. The GDI 446 in general can include a process that can generategraphical object draw commands. The GDI 446 in this example embodimentcan be configured to pass its output to the remote display subsystem 454where the commands are formatted for the display driver that is attachedto the session. In certain example embodiments, one or more physicaldisplays can be attached to the computer system 400, e.g., in a remotedesktop situation. In these example embodiments the remote displaysubsystem 454 can be configured to mirror the draw commands that arerendered by the display driver(s) of the remote computer system andtransmit the mirrored information to the client 401 via a stack instanceassociated with the session. In another example embodiment, where thecomputer system 400 is a remote presentation session server, the remotedisplay subsystem 454 can be configured to include virtual displaydriver(s) that may not be associated with displays physically attachedto the computer system 400, e.g., the computer system 400 could berunning headless. The remote display subsystem 454 in this embodimentcan be configured to receive draw commands for one or more virtualdisplays and transmit them to the client 401 via a stack instanceassociated with the session. In an embodiment of the present invention,the remote display subsystem 454 can be configured to determine thedisplay resolution for each display driver, e.g., determine the displayresolution of the virtual display driver(s) associated with virtualdisplays or the display resolution of the display drivers associatedwith physical displays; and route the packets to the client 401 via theassociated protocol stack instance.

In some example embodiments, the session manager 416 can additionallyinstantiate an instance of a logon process associated with the sessionidentifier of the session that can be configured to handle logon andlogoff for the session. In these example embodiments drawing commandsindicative of the graphical user interface associated with the logonprocess can be transmitted to the client 401 where a user of the client401 can input an account identifier, e.g., a username/passwordcombination, a smart card identifier, and/or biometric information intoa logon screen. The information can be transmitted to computer system400 and routed to the engine 412 and the security subsystem 450 of thesession core 444. For example, in certain example embodiments the engine412 can be configured to determine whether the user account isassociated with a license; and the security subsystem 450 can beconfigured to generate a security token for the session.

In a remote desktop environment, the user graphics are rendered at theserver for each user. The user graphics can include text images andnatural images. The resulting graphics may then be sent to the clientfor display and interaction. To reduce the bandwidth requirements on thenetwork, graphics may be compressed before transmission to the client.It is desirable that the compression technique be efficient with lowlatency. The use of progressive encoding and spoiling schemes as will bedescribed herein supports the reduction of bandwidth usage.

Various systems and methods exist for encoding and decoding electronicinformation, including graphics data. In an exemplary embodiment, anencoding and decoding system may include a dividing module thatinitially divides a source image into data regions. A frame differencingmodule may then compare each data region as the data region is updatedacross the frames and determine whether the region has been updated andif so, what portions of the region have been updated. The framedifferencing module can then send the updated and non-updated region tovarious processing modules that convert the regions into correspondingupdated and non-updated data portions. In an embodiment, a quantizer mayperform a compression procedure upon the data portions to generatecompressed data according to an adjustable quantization parameter. Anadaptive entropy selector may then select one of a plurality ofavailable entropy encoders to perform an entropy encoding procedure tothereby produce encoded data. The entropy encoder may also utilize afeedback loop to adjust the quantization parameter in light of currenttransmission bandwidth characteristics.

In various methods and systems disclosed herein, aspects of theprocessing and handling of the various processes, such as thosedescribed above, may be used to provide more efficient processing andthus a more timely and a richer user experience. The methods and systemsalso provide such graphics support when the network and/or systemresources become congested or otherwise less available. The embodimentsdisclosed herein for encoding and transmitting graphics data may beimplemented using various combinations of hardware and softwareprocesses. In some embodiments, functions may be executed entirely inhardware. In other embodiments, functions may be performed entirely insoftware. In yet further embodiments, functions may be implemented usinga combination of hardware and software processes. Such processes mayfurther be implemented using one or more CPUs and/or one or morespecialized processors such as a graphics processing unit (GPU) or otherdedicated graphics rendering devices.

Referring to FIG. 5, illustrated is an overview of various functionsassociated with the encoding and transmitting processes discussedherein. Various aspects of the illustrated process may be modified toimprove the throughput and efficiency of the processes. Process 500illustrates the capturing and buffering of a client frame. Process 510illustrates the dividing of the captured and buffered client frame intodata regions. Process 520 illustrates the comparing of the regions toregions in previously captured and buffered client frames. Process 530illustrates the process of progressive encoding and spoiling of the dataregions. Process 540 illustrates the transmitting of the encoded andnon-spoiled data regions. Once transmitted, process 550 illustrates thatthe received frame may be decoded. Process 560 illustrates that thereceive buffers may be managed to track changed regions and portions ina frame. Process 570 illustrates that the display frame buffers may beused to drive the display controller in an efficient manner.

Various embodiments may incorporate a progressive encoding and spoilingscheme that the server uses to encode and transmit a portion of a screento the client. FIGS. 6 and 7 provide an example of a screen region thatthe server needs to encode and transmit to the client. Various means,such as a screen scraping function in Remote Desktop Protocol (RDP), canbe used to allow the server to read graphics data representative ofspecific regions or portions thereof on the screen and to determinewhich regions or portions are changing. Whenever a region or a portionof a region changes, RDP drivers may provide the coordinates of theregion or the portion thereof that is changing. FIG. 6 depicts anexample of a screen with a first frame 601 and a second frame 602, thesecond frame 602 being an adjacent update of the first frame 601. Inthis example, the first frame 601 contains region 610 and region 620.Region 610 contains text image content while region 620 contains naturalimage content. The server encodes and transmits the first frame 601 tothe client for display and interaction. Afterwards, the server encodesand transmits the second frame 602 to the client for display andinteraction. In this second encoding and transmitting step, the region610 in the first frame 601 should not be processed a second time becausethe region 610 is no longer rendered in the second frame 602. Incomparison, region 630 and region 640 are new regions in the secondframe 602 and need to be encoded and transmitted to the client for thefirst time. In addition, the region 620 is the same region 620 encodedand transmitted in the first frame 601 and needs to be processed asecond time because the region 620 is also rendered in the second frame602. However, the region 620 in the second frame 602 contains portionsthat are occluded by the region 630 and the region 640 and portions thatare non-occluded by any other graphics object.

FIG. 7 further exemplifies the occluded and non-occluded portions of theregion 620 depicted in FIG. 6. Portion 702, portion 704, portion 706,and portion 708 are non-occluded portions of the region 620 because theyare not blocked by other graphics objects (e.g. the region 630 and theregion 640). As such, the non-occluded portions (e.g. portions 702, 704,706, and 708) when rendered on a display would be visible to a user. Onthe other hand, portion 710 is occluded by the region 630 in the secondframe 602. Similarly, portion 712 is occluded by the region 640 in thesecond frame 602. The occluded portions (e.g. portions 710 and 712) whenrendered on a display would not be visible to a user because of otherblocking graphics objects (e.g. regions 630 and 640). To reducebandwidth usage and the amount of data to be processed, the server needsto only encode and transmit data representative of the non-occludedportions (e.g. portions 702, 704, 706, and 708) of region 620 in thesecond frame 602. The occluded portions (e.g. portions 710 and 712) canbe said to be spoiled. Data representative of spoiled regions orportions need not be encoded, transmitted, or further processed by theserver. Because the amount of data to be encoded and transmitted isreduced, the spoiling of the occluded portions will result in areduction in the network bandwidth usage, which will in-turn result in areduction in network latencies and will improve the remote userexperience.

To further optimize the bandwidth usage and the amount of data to beprocessed, various embodiments may incorporate a progressive encodingand transmitting scheme. The server can determine an overall quality forthe remote presentation session. The quality can be used by an encoderwithin the server to encode the data to the client. For example, a 100%quality can represent the maximum quality the encoder can encode thedata and can equate to the overall quality of the remote presentationsession. In one embodiment, the server can encode and transmit datarepresentative of a region in a first frame at a first quality. Forexample, the server can encode and transmit the region 620 in the firstframe 601 at, say, a 50% quality. The server can subsequently encode andtransmit data representative of the same region in a second frame at asecond quality. For example, the server can encode and transmit theregion 620 in the second frame 602 at, say, a 75% quality.

In one embodiment, the server can progressively improve the quality usedto encode and transmit the graphics data to the client. For example, thesecond quality at which the server is encoding and transmitting the datacan be higher than the first quality at which the server already encodedand transmitted the data. The remote user will experience a graphicsimage display that is gradually improving with each new frame containinginformation about the image.

In a further embodiment, the second quality at which the server encodesand transmits the data can be set as an increment over the firstquality. The increment over the first quality can be a pre-determinedpercentage or can be dynamically adjusted based on various factors suchthe available network bandwidth and the amount of data to be processed.For example, and referring to FIG. 6, the region 620 in the first frame601 can be encoded and transmitted at a first quality of 50%. The severcan then determine that an increment of 25% is needed when encoding andtransmitting the region 620 in the second frame 602. Therefore, theserver can encode and transmit the region 620 in the second frame 602 ata second quality of 75%. In parallel, because the region 640 in thesecond frame 602 has not been previously processed, the server canencode and transmit the region 640 at the first quality of 50%. As such,different regions and portions in the same graphics frame can be encodedand transmitted at different quality levels.

In one embodiment, the quality that the server uses to encode andtransmit the graphics data can be dynamically adjusted as a function ofthe available network bandwidth and/or the amount of data to beprocessed. For example, after the server encodes and transmits the firstframe, the server could detect the available network bandwidth and theamount of data to be processed. The server could then determine a targetquality to be used in processing the second frame. This dynamic qualityadjustment ensures that a high quality is used with the availablenetwork bandwidth and/or amount of data to be processed. For example,when the server determines that sufficient network bandwidth exists, theserver can encode and transmit the graphics data at a 100% quality.

In one embodiment, to ensure readability of text content in a region orin a portion of a region, the server may not apply the progressiveencoding and spoiling scheme to the graphics data comprising a textimage contained in the region or in the portion of the region.Alternatively, the server can apply a progressive encoding and spoilingscheme with a 100% quality for the text image region or portion and canapply a different quality for the natural image regions and portions.For example, the region 610 in the first frame 601 depicted in FIG. 6has text image content, while region 620 has natural image content. Theserver encoding and transmitting the first frame 601 can encode andtransmit the region 610 at a 100% quality, and the region 620 at adifferent quality (e.g. 50%). Similarly, the server can encode andtransmit the text image region 630 in the second frame 602 at a 100%quality, and the natural image regions 620 and 640 at different qualitylevels (e.g. 75% for the region 620 and 50% for the region 640).

In an embodiment, when the quality of the encoded and transmitted regionis a 100%, the region can be marked as having full fidelity. The regioncan then be used by other components in the RDP such as componentsassociated with data caching, delta detection, and motion detection. Assuch, the full fidelity region need not be encoded and transmitted againif the full fidelity region re-appears in a future frame. Thus,implementing a full fidelity marking further reduces the bandwidth usageby reducing the amount of data to be processed.

In order to reduce network latencies and improve the remote userexperience when the available network bandwidth and/or the amount ofdata to be processed impose constraints on the encoding and transmittingschemes, an embodiment can use a combination of progressive encoding andspoiling techniques. For progressive encoding, the embodiment uses ahigher quality (e.g. 100%) for text image regions, a lower quality (e.g.50%) for natural image regions that are encoded and transmitted for thefirst time, and a quality increment (e.g. 25%) over the last quality forsubsequent encoding and transmitting of the natural image regions. Inaddition, spoiled regions or portions thereof are not encoded andtransmitted. As an example and referring to FIGS. 6 and 7, the followingquality levels are applied:

-   -   100% for the text image region 610 in the first frame 601 and        the text image region 630 in the second frame 602. Because of        the 100% quality, the region 610 and the region 630 are marked        as full fidelity regions.    -   50% for the region 620 in the first frame 601 and for the region        640 in the second frame 602 because both regions contain natural        image content and are processed for the first time in the        respective frames.    -   75% for the region 620 in the second frame 602 because the        natural region 620 was previously processed in the first frame        601. In addition, the region 620 contains occluded and        non-occluded portions. Only the non-occluded portions 702, 704,        706, and 708 are encoded and transmitted to the client at the        75% quality, while the occluded portions 710 and 712 are spoiled        and not encoded and transmitted.

The amount of processing associated with encoding regions at incrementalqualities and spoiling portions thereof as needed, and the networkbandwidth usage associated with transmitting these regions are reducedin comparison to a non-progressive encoding and transmitting scheme. Inother words, the amount of data associated with encoding a region can bereduced with each frame where the region re-appears because the regionis encoded at incremental qualities across the frames and portionsthereof are spoiled as necessary.

In various embodiments, an encoding context can be created for a dataregion that appear for the first time in a frame. In this encodingcontext, a first quality is set as a target quality. Subsequently, theencoding context is updated when the region appears in a second frame,and/or when occluded portions of the region no longer need to be encodedand transmitted. The target quality in the encoding context is alsoupdated and is set as an increment over the first quality. Referring toregions and portions in FIGS. 6 and 7, the following pseudo code for theencoding context of the natural image regions can be used:

The natural image region 620 in the first frame 601:

-   -   pContext1=CreateEncodingContext(Region 620)    -   pEncoder→Encode(pContext1, {Region 620}, nTargetQuality (e.g.        50%), &pbBuffer1, cbBufefr1)

The natural region 620 and the natural image region 640 in the secondframe 602:

-   -   pContext2=CreateEncodingContext(Region 640)    -   pEncoder→Encode(pContext2, {Region 640}, nTargetQuality(e.g.        50%), &pbBuffer2, cbBuffer2)    -   pEncoder→Encode(pContext1, {portion 702, portion 704, portion        706, portion 708}, nTargetQuality(e.g. 75%), &pbBuffer3,        cbBuffer3)

In an embodiment, in order to ensure the coherence of the framedisplayed by the client to the remote user, the client may not display asecond decoded graphics frame until all the regions in the firstgraphics frame have been decoded and displayed at the quality levelsassociated with the progressive encoding and spoiling of the firstframe.

In an embodiment, an entropy encoder function may perform an entropyencoding procedure to generate encoded graphics data. In certainembodiments, the entropy encoding procedure further reduces the bit rateof the encoded graphics data by substituting appropriate codes forcorresponding bit patterns in the encoded graphics data. In oneembodiment, a GPU may be provided graphics data with data regions and/ornon-occluded data portions that need to be encoded. In this manner, theprocess effectively implements a progressive encoding and spoilingscheme in concert with the client where the resulting decoded graphicsdata is maintained and displayed. As such, the server can perform theentropy encoding on the most needed data portions at a certain qualityand thus reduces latencies from the encoding process.

FIG. 8 depicts an exemplary operational procedure for processinggraphics data for transmission to a client including operations 800,802, 804, 806, 808, and 810. Operation 800 begins the operationalprocedure and operation 802 illustrates receiving graphics datarepresenting a client screen associated with a remote presentation.Operation 804 illustrates detecting which regions of the client screenneed to be processed with a progressive encoding and spoiling scheme.Operation 806 illustrates creating a progressive encoding context foreach of the regions to be processed with a progressive encoding andspoiling scheme. Operation 808 illustrates performing the progressiveencoding context and spoiling of a region across multiple graphicsframes for each of the created encoding context. Operation 810illustrates transmitting the progressively encoded and non-spoiledregion to the client.

FIG. 9 depicts an exemplary system for processing graphics data fortransmission to a client computer as described above. System 900comprises a processor 910 and memory 920. In an embodiment, theprocessor 910 can be implemented as processing unit 21 in FIG. 1, whilethe memory 920 can be implemented as having some or all of thecomponents of the system memory 22 in FIG. 1. The memory 920 furthercomprises computer instructions configured to cause the system toprocess graphics data for transmission to a plurality of clientcomputers. Block 922 illustrates receiving graphics data representing aclient screen associated with a remote presentation. Block 924illustrates detecting which regions of the client screen need to beprocessed with a progressive encoding and spoiling scheme. Block 926illustrates creating a progressive encoding context for each of theregions to be processed with a progressive encoding and spoiling scheme.Block 928 illustrates performing the progressive encoding context andspoiling of a region across multiple graphics frames for each of thecreated encoding context. Block 930 illustrates transmitting theprogressively encoded and non-spoiled region to the client.

Any of the above mentioned aspects can be implemented in methods,systems, computer-readable media, or any type of manufacture.

The foregoing detailed description has set forth various embodiments ofthe systems and/or processes via examples and/or operational diagrams.Insofar as such block diagrams, and/or examples contain one or morefunctions and/or operations, it will be understood by those within theart that each function and/or operation within such block diagrams, orexamples can be implemented, individually and/or collectively, by a widerange of hardware, software, firmware, or virtually any combinationthereof.

It should be understood that the various techniques described herein maybe implemented in connection with hardware or software or, whereappropriate, with a combination of both. Thus, the methods and apparatusof the disclosure, or certain aspects or portions thereof, may take theform of program code (i.e., instructions) embodied in tangible media,such as floppy diskettes, CD-ROMs, hard drives, or any othermachine-readable storage medium wherein, when the program code is loadedinto and executed by a machine, such as a computer, the machine becomesan apparatus for practicing the disclosure. In the case of program codeexecution on programmable computers, the computing device generallyincludes a processor, a storage medium readable by the processor(including volatile and non-volatile memory and/or storage elements), atleast one input device, and at least one output device. One or moreprograms that may implement or utilize the processes described inconnection with the disclosure, e.g., through the use of an applicationprogramming interface (API), reusable controls, or the like. Suchprograms are preferably implemented in a high level procedural or objectoriented programming language to communicate with a computer system.However, the program(s) can be implemented in assembly or machinelanguage, if desired. In any case, the language may be a compiled orinterpreted language, and combined with hardware implementations.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in form and detail may bemade without departing from the scope of the present invention as setforth in the following claims. Furthermore, although elements of theinvention may be described or claimed in the singular, the plural iscontemplated unless limitation to the singular is explicitly stated.

What is claimed:
 1. A system for encoding and transmitting graphics datain a remote desktop environment, comprising: a processor; and a memorycommunicatively coupled to the processor, the memory bearing processorinstructions that, when executed by the processor, cause the system to:process a first region of a user remote desktop; determine a first dataset representative of a portion of a first region; transmit the firstdata set to a remote desktop client computer at a first quality; processa second region of the user remote desktop, the second region includingat least one previously processed sub-region and at least one notpreviously processed sub-region; determine a second data setrepresentative of a non-occluded portion of the second region, thenon-occluded portion being a portion of the region that is visible whenrendered on a display; and transmit the second data set to the remotedesktop client computer, wherein a portion of the second data setincluding the at least one previously processed sub-region istransmitted at a second quality and a portion of the second data setincluding the at least one not previously processed sub-region istransmitted at the first quality.
 2. The system of claim 1, wherein thesecond quality is higher than the first quality.
 3. The system of claim1, wherein the second quality is a fixed minimal increment over thefirst quality.
 4. The system of claim 1, wherein the second quality isnear or at a maximum quality.
 5. The system of claim 1, wherein thesecond quality is a function of network bandwidth connecting the remotedesktop server computer with the remote desktop client computer andother computing devices.
 6. The system of claim 1, wherein the secondquality is a function of an amount of data to be processed.
 7. Thesystem of claim 1, wherein the second quality is a function of networkbandwidth connecting the remote desktop server computer with the remotedesktop client computer and other computing devices and an amount ofdata to be processed.
 8. The system of claim 1, wherein the secondquality is near or at a maximum quality for a data set representative ofa portion of a region that is a text image.
 9. The system of claim 1,wherein a data set representative of an occluded portion of a region isnot sent to the remote desktop client computer, the occluded portionbeing a portion of the region that is not visible when rendered on adisplay.
 10. The system of claim 1, wherein a data set representative ofa non-occluded portion is cached when a first quality or a secondquality of the data set is 100%.
 11. A method for encoding andtransmitting graphics data in a remote desktop environment, comprising:processing a first region of a user remote desktop; determining a firstdata set representative of a portion of a first region; transmitting thefirst data set to a remote desktop client computer at a first quality;processing a second region of the user remote desktop, the second regionincluding at least one previously processed sub-region and at least onenot previously processed sub-region; determining a second data setrepresentative of a non-occluded portion of the second region, thenon-occluded portion being a portion of the region that is visible whenrendered on a display; and transmitting the second data set to theremote desktop client computer, wherein a portion of the second data setincluding the at least one previously processed sub-region istransmitted at a second quality and a portion of the second data setincluding the at least one not previously processed sub-region istransmitted at the first quality.
 12. The method of claim 11, whereinthe second quality is higher than the first quality.
 13. The method ofclaim 11, wherein the second quality is a function of network bandwidthconnecting the remote desktop server computer with the remote desktopclient computer and other computing devices and an amount of data to beprocessed.
 14. The method of claim 11, wherein the second quality isnear or at a maximum quality for a data set representative of a portionof a region that is a text image.
 15. The method of claim 11, wherein adata set representative of an occluded portion of a region is not sentto the remote desktop client computer, the occluded portion being aportion of the region that is not visible when rendered on a display.16. A computer-readable storage device for encoding and transmittinggraphics data in a remote desktop environment, bearing computer-readableinstructions that, when executed on a computer, cause the computer toperform operations comprising: processing a first region of a userremote desktop; determining a first data set representative of a portionof the first region; transmitting the first data set to a remote desktopclient computer at a first quality; processing a second region of theuser remote desktop, the second region including at least one previouslyprocessed sub-region and at least one not previously processedsub-region; determining a second data set representative of anon-occluded portion of the second region, the non-occluded portionbeing a portion of the region that is visible when rendered on adisplay; and transmitting the second data set to the remote desktopclient computer, wherein a portion of the second data set including theat least one previously processed sub-region is transmitted at a secondquality and a portion of the second data set including the at least onenot previously processed sub-region is transmitted at the first quality.17. The computer-readable storage device of claim 16, wherein the secondquality is higher than the first quality.
 18. The computer-readablestorage device of claim 16, wherein the second quality is a function ofnetwork bandwidth connecting the remote desktop server computer with theremote desktop client computer and other computing devices and an amountof data to be processed.
 19. The computer-readable storage device ofclaim 16, wherein the second quality is near or at a maximum quality fora data set representative of a portion of a region that is a text image.20. The computer-readable storage device of claim 16, wherein a data setrepresentative of an occluded portion of a region is not sent to theremote desktop client computer, the occluded portion being a portion ofthe region that is not visible when rendered on a display.